Pre-recorded voice message delivery systems which place calls to recipients' telephones have conventionally been optimized for delivery to a live person. These delivery systems detect when a call has been answered and begin playing pre-recorded messages (or provide some kind of "audio logo") as soon as possible in order to discourage the live party from hanging up before the message can be delivered.
Other conventional pre-recorded message delivery systems (and some live telemarketing systems), attempt to distinguish between a live answer and an answering device, and deliver a message (or connect a service representative) accordingly. The presence of an answering device is conventionally detected by live callers monitoring for a tone typically associated with answering devices. Due to the large variation among tones produced by different models of answering devices, automatically distinguishing an answering device tone from other sounds likely to be present in the call has proven unreliable.
Still other conventional pre-recorded message delivery systems begin to play a pre-recorded message as soon as the call has been answered. These systems do not distinguish when an answering machine begins to record. Rather, these systems play the same message, or portions thereof, more than once to ensure that the entire message is recorded by the answering device. This results in a recording on the recipient answering machine that will most likely not start at the beginning of the pre-recorded message.
In yet another variation, some systems attempt to distinguish live callers from answering machines. Live parties are distinguished typically by the presence of a continuous period of silence of approximately 1 to 1.5 seconds in the 4 seconds after detecting speech from the call. When this occurs, the call is classified as to a live party and a message is immediately begun or a representative immediately connected in order to discourage the called party from hanging up. Otherwise, after 4 seconds of speech has been received, these systems wait for 3 seconds of continuous silence and then deliver a message to what is classified as an answering machine. Unfortunately, with this system, answering machines will sometimes be falsely classified as live parties. This may result in no message, a wrong message, or only part of a message being left on the answering device.
It would be desirable to deliver complete, pre-recorded voice messages directly to answering devices (or voice messaging systems) without having to detect an answering machine tone. It would also be desirable to optimize message delivery systems for voice mail delivery to deliver correct, complete, pre-recorded voice messages to voice messaging systems.